Binding agent mixture, coating agents containing said binding agent mixture, and coatings produced from said coating agents, said coatings having a high scratch resistance, high weathering stability, and good optical properties

ABSTRACT

Binder mixture comprising a hydroxyl-containing compound (A), and at least 1.0% by weight, based on the nonvolatile constituents of the binder mixture, of a phosphorus- and nitrogen-containing catalyst (D) for the crosslinking of silane groups, wherein the hydroxyl-containing compound (A) comprises a hydroxyl-functional polyester having on average at least one hydroxyl function of the polyester esterified with a C8 to C9 monocarboxylic acid, and the catalyst (D) is blocked with at least one tertiary amine of the formula (I) 
     
       
         
         
             
             
         
       
     
     where R 1  is an acyclic aliphatic or araliphatic hydrocarbon radical having at least 3 C atoms, R 2  is an acyclic aliphatic or araliphatic hydrocarbon radical which is the same or different from R 1  and/or R 3 , and R 3  is hydrogen or an acyclic aliphatic or araliphatic hydrocarbon radical which is the same or different from R 1  and/or R 2 .

The present invention provides binder mixtures comprising at least onehydroxyl-containing compound (A) and at least 1.0% by weight, based onthe nonvolatile constituents of the mixture, of at least one phosphorus-and nitrogen-containing catalyst (D) for the crosslinking of silanegroups.

The invention also relates to coating compositions based on the bindermixture and also multistage coating methods using these coatingcompositions, and also the use of the coating compositions as clearcoatmaterial and application of the coating method for automotive OEMfinishing and automotive refinish.

EP-A-1 273 640 describes coating compositions comprising a polyolcomponent and a crosslinker component consisting of aliphatic and/orcycloaliphatic polyisocyanates, 0.1 to 95 mol % of the free isocyanategroups originally present having undergone reaction withbisalkoxy-silylamine. As catalyst these coating compositions comprisecustomary catalysts, such as organotin compounds, dibutyltin dilauratefor example, amines or sulfonic acid-based catalysts, p-toluenesulfonicacid, for example. The coating compositions described in EP-A-1 273 640can be used for OEM finishing and exhibit good scratch resistance inconjunction with good stability toward environmental influences.However, these coating compositions have a particularly strong tendencytoward post-crosslinking, since conversion on thermal curing afterapplication is inadequate. This has adverse effects especially for theweathering stability.

WO2008/074489 discloses coating compositions which comprise at least onehydroxyl-containing compound (A) and at least one isocyanato-containingcompound (B), with one or more constituents of the coating compositioncontaining hydrolyzable silane groups. It is essential to the inventionthat the coating compositions described therein comprise as catalyst(D), for the crosslinking of the silane groups, phosphorus-containingcatalysts, more particularly amine-blocked partial ethylhexyl esters ofphosphoric acid. Examples of amines with which the phosphoric esters areblocked are tertiary amines, preferably triethylamine. The coatingcompositions described therein lead to coatings having a high scratchresistance in conjunction with good weathering stability. The to coatingcompositions are to be improved still further, however, in respect oftheir optical properties, more particularly in respect of theirappearance. Moreover, the electrical resistance of these coatingcompositions is inadequate.

Especially if the coating materials are electrostatically charged in thecourse of their application, the electrical resistance of the coatingmaterials is of particular importance. Depending on the plant, it may benecessary on safety grounds for the coating materials, and also, in thecase of 2-component coating compositions, the individual coatingcompo-nents, not to have less than a particular electrical resistancevalue. Against this background there is interest in providing coatingmaterials which do not fall below a certain minimum level in respect ofelectrical resistance. In the field of automotive OEM finishing,therefore, the usual requirement is for the coating compositions or, inthe case of 2-component coating compositions, the individual coatingcomponents to have an electrical resistance of at least 200 kohm,preferably at least 250 kohm, and more preferably at least 350 kohm. Thelimiting values acquired are each plant-specific limiting values and mayvary according to the specific mandates of the plant manufacturers. Thehighest limiting values in each case are particularly preferred onaccount of the fact that they meet the mandates of a variety of plants.

The electrical resistance is investigated with the aid of a dip probemeasuring cell, with a conductivity meter of type LC 2 from Byk Gardner,in accordance with DIN 55667 at 25° C.

Finally, the as yet unpublished German patent application DE 102008060454.2-43 describes coating compositions comprising at least onehyperbranched, dendritic, hydroxyl-functional polyester (A) having an OHnumber ≧180 mg KOH/g as measured via DIN 53240, and also polyisocyanates(B) which comprise at least partly hydrolyzable silane groups. Used ascatalyst (D) for the crosslinking of the silane groups arephosphorus-containing catalysts, more particularly amine-blocked partialethylhexyl esters of phosphoric acid. Examples given of amines withwhich the phosphoric esters are blocked are tertiary amines, such asdimethyldodecylamine or triethylamine, and also bicyclic amines, such asdiazabicyclononene (DBN), diazabicyclooctane (DABCO), anddiazabicycloundecene (DBU), for example. Information as to how theelectrical resistance of the binder mixtures and of the coatingcompositions can be set, however, is absent from that specification. Noris there any description of the use of amines comprising at least onebranched aliphatic hydrocarbon radical for the purpose of blocking thephosphoric esters.

Problem

It was an object of the present invention, therefore, to provide bindermixtures and coating compositions produced from them, particularly forthe clearcoat in OEM finishes and automotive refinishes, that lead tocoatings having a combination of high scratch resistance, good acidresistance, and good weathering stability, with at the same time a verygood overall appearance.

The aim was therefore to provide coating compositions which lead to anetwork with a high degree of weathering stability and which at the sametime ensure high acid resistance. In addition, the coating compositionsare to lead to coatings which already have a high degree ofscratchproofing straight after thermal curing, and in particular a highlevel of gloss retention after scratch exposure. Moreover, the coatingsand coating systems, especially the clearcoat systems, ought to be ableto be produced even in film thicknesses >40 μm without stress cracksoccurring. This is a key requirement for the use of the coatings andcoating systems, particularly of the clearcoat systems, in thetechnologically and esthetically particularly demanding field ofautomotive OEM finishing.

At the same time the binder mixtures and the coating compositionsproduced from them ought not to fall below a certain minimum level inrespect of their electrical resistance. In the field of automotive OEMfinishing a customary requirement is that the electrical resistance notonly of the individual coating components, such as the binder mixture,but also of the coating compositions produced from them be at least 200kohm, preferably at least 250 kohm, and more preferably at least 350kohm.

Finally the coating compositions ought, however, also to exhibit goodtransparency (low haze values) and good leveling and lead to coatingshaving a good overall appearance.

Solution to the Problem

In the light of the above objectives, binder mixtures based on aproticsolvents have been found, comprising

at least one hydroxyl-containing compound (A) andat least 1.0% by weight, based on the nonvolatile constituents of themixture, of at least one phosphorus- and nitrogen-containing catalyst(D) for the crosslinking of silane groups,wherein the mixture comprises

-   (i) as hydroxyl-containing compound (A) at least one    hydroxyl-functional polyester (A) in which on average at least one    hydroxyl function of the polyester is esterified with at least one    acid selected from the group of the isomeric C8 to C9 monocarboxylic    acids, and-   (ii) as catalyst (D) at least one phosphorus-containing catalyst    blocked with at least one amine of the formula (I)

-   -   where    -   R₁ is an acyclic aliphatic or araliphatic hydrocarbon radical        having at least 3 C atoms,    -   R₂ is an acyclic aliphatic or araliphatic hydrocarbon radical        which is the same or different from R₁ and/or R₃, and    -   R₃ is hydrogen or an acyclic aliphatic or araliphatic        hydrocarbon radical which is the same or different from R₁        and/or R₂.

The invention further provides coating compositions based on the bindermixture, and also multistage coating methods using these coatingcompositions, and also the use of the coating compositions as clearcoatmaterial and application of the coating method for automotive OEMfinishing and automotive refinish, and also for the coating of parts forinstallation in or on automobiles.

In the light of the prior art it was surprising and unforeseeable forthe skilled worker that the objects on which the present invention wasbased could be achieved by means of the binder mixture of the inventionand by means of the coating composition of the invention based on saidbinder mixture.

Thus it is particularly surprising that the binder mixtures of theinvention and the corresponding coating compositions of the invention,in spite of the relatively high fraction of catalyst (D), have anelectrical resistance of at least 200 kohm, preferably at least 250kohm, and more preferably at least 350 kohm, as required in theautomotive OEM finishing segment.

At the same time the coating compositions of the invention produce newcoatings and coating systems, especially clearcoat systems, which arehighly scratchproof and, in contrast to common, highly crosslinkedscratchproof systems, are acid-resistant. Moreover, the coatings andcoating systems of the invention, especially the clearcoat systems, canbe produced even in film thicknesses >40 μm without stress cracksoccurring. Consequently the coatings and coating systems of theinvention, especially the clearcoat systems, can be used in thetechnologically and esthetically particularly demanding field ofautomotive OEM finishing. In that context they are distinguished byparticularly high carwash resistance and scratch resistance. The highscratch resistance of the coatings exists in particular directly aftertheir final curing, and so the coatings can be handled without problemsimmediately after final curing.

Furthermore it is surprising that the binder mixtures and the coatingcompositions at the same time also exhibit good transparency (low hazevalues) and good leveling and lead to coatings having a good overallappearance. Finally, the components according to the invention can beprepared with particular ease and with very good reproducibility and onapplication of the coating material cause no significant toxicologicalor environmental problems.

DESCRIPTION OF THE INVENTION The Binder Mixture of the Invention TheHydroxyl-Functional Polyesters (A)

It is essential to the invention that the binder mixtures of theinvention comprise at least one hydroxyl-functional polyester where onaverage at least one hydroxyl function of the hydroxyl-functionalpolyester is esterified with at least one acid selected from the groupof the isomeric C8-C9 monocarboxylic acids. In particular it is possiblein this way to achieve a satisfactory residual gloss in the resultantcoatings. The afore-described esterification with at least one C8-C9carboxylic acid is also referred to synonymously as “acid modification”.

The radical of the isomeric C8-C9 monocarboxylic acid is preferablysaturated. Clearcoat compositions of this kind exhibit good weatheringstability.

Particularly advantageous properties in the sense of the inventionresult when the radical of the C8-C9 monocarboxylic acid is the radicalof octanoic acid or isononanoic acid. With particular preferenceisononanoic acid is the C8-C9 monocarboxylic acid used.

Preferred for esterification with the isomeric C8-C9 monocarboxylicacids are hyperbranched, dendritic hydroxyl-functional polyesters.Hyperbranched, dendritic compounds, i.e., hyperbranched dendriticmacromolecules and dendrimers, can be described generally asthree-dimensional, highly branched molecules having a treelikestructure. Dendrimers are highly symmetrical, whereas similarmacromolecules referred to as being hyperbranched and/or dendritic maybe asymmetric to a certain extent and nevertheless retain the highlybranched treelike structure. Hyperbranched and dendritic macromoleculescan typically be prepared starting from an initiator or nucleus havingone or more reactive sites and a number of branching layers(“generations”) and, if appropriate, a layer of chain-ending molecules(divergent synthesis approach). The continued replication of branchinglayers normally produces an increased multiplicity of branching, and ifappropriate or if desired, an increased number of end groups. The layersare referred to typically as generations, to and the branches asdendrons.

The polyester (A) used in accordance with the invention and modifiedwith an isomeric C8-C9 monoarboxylic acid preferably has a hydroxylnumber of ≧150 mg KOH/g, more particularly a hydroxyl number of >180 mgKOH/g, preferably 185-240 mg KOH/g, determined in accordance with DIN53240. Use is made in particular of polyesters which have a hydroxylfunctionality (given via the number of free and of esterified hydroxylgroups of the hydroxyl-functional polyester) of greater than 16. Suchclearcoat compositions possess a sufficient microhardness (i.e., >90N/mm2, determined in accordance with DIN EN ISO 14577 using theFischerscope instrument from Fischer, with a maximum force of 25.6 mN),and are scratchproof and chemical-resistant.

Likewise preferred are hydroxyl-functional polyesters (A) which have anacid number ≦8.0, preferably 0-6.0, determined in accordance with DIN53402. Such acid numbers of the polyesters result in bettercompatibility of these polyesters with other coating base materials, andin improved leveling.

Further preferred are hydroxyl-functional polyesters (A) having anumber-average molecular weight of 1500-4000 g/mol, preferably 2000-3500g/mol, determined via GPC with a polystyrene standard in THF with 0.1mol/l acetic acid. A low molecular weight of this kind in combinationwith a correspondingly low molecular weight distribution on the part ofthe dendritic polyester leads generally to improved compatibility.

Preference is given to using polyesters with a polydispersity Mw/Mn <4.Particularly good properties result when the polyester has an even lowerpolydispersity, i.e., Mw/Mn <2.5, more particularly Mw/Mn 2.0.

It is particularly preferred to use monodisperse or substantiallymonodisperse polyesters, which can be prepared easily, reliably, andreproducibly, and whose properties and end structures can be easily andconveniently modified.

Polyesters of this kind can be prepared via a partial esterification ofa hydroxyl-functional polyester, which is preparable in turn via amethod for the synthesis of a dendritic polymeric polyalcohol (polyesterpolyol) having reactive and, if desired, protected hydroxyl end groups,in accordance with EP 991 690 B1,

-   -   where the polymeric polyalcohol possesses n dendritic branches        originating from a monomeric or polymeric initiator molecule        having n reactive groups (A1), each branch comprising g        branching generations, each generation comprising at least one        polymeric or monomeric branching chain extender having three        functional groups, of which at least two are reactive hydroxyl        groups (A2) and one is a carboxyl group (A3) which is reactive        with the reactive group (A1) and/or with the hydroxyl groups        (A2), and, if desired, at least one spacer generation which        comprises at least one spacer chain extender having two        functional groups, of which one is a protected hydroxyl group        (A2″) and one is a group (A4) which is reactive with a hydroxyl        group, with n and g being whole numbers and being at least 1,    -   where (i) the two hydroxyl groups (A2) of the monomeric or        polymeric chain branching extender used are acetal-protected        hydroxyl groups (A2′), the protection by acetal being obtained        through a reaction between the two hydroxyl groups (A2) and an        acetal-forming carbonyl compound; and    -   (ii) where a first branching generation is added to the        initiator molecule through reaction between the reactive group        (A1) and the carboxyl group (A3), in a molar ratio of the        reactive groups (A1) to the carboxyl groups (A3) of at least 1,        to give a polymeric polyalcohol having acetal-protected hydroxyl        groups (A2′) and n dendritic branches which comprise one        generation, the acetal-protected hydroxyl groups (A2′) being        deprotected, if desired, by means of acetal cleavage, to give a        polymeric polyalcohol having reactive hydroxyl groups (A2); and    -   (iii) where further branching generations are added in g-1        repeated steps, through reaction between reactive hydroxyl        groups (A2), obtained by deprotection by means of acetal        cleavage, and carboxyl groups (A3), in is a molar ratio of        hydroxyl groups (A2) to carboxyl groups (A3) of at least 1, to        give a polymeric polyalcohol having acetal-protected hydroxyl        groups (A2′) and n dendritic branches which comprise two or more        generations, the acetal-protected hydroxyl groups (A2′) being        deprotected, if desired, by means of acetal cleavage, to give a        polymeric polyalcohol having reactive hydroxyl groups (A2), and    -   if desired, (iv) step (ii) and/or each repetition of step (iii)        individually is followed by        (a) a partial protection, such as protection as an acetal, ketal        and/or ester, for example, of available reactive hydroxyl groups        (A2), giving a polymeric polyalcohol having at least one        reactive hydroxyl group (A2) for use in step (iii) or in a        repeated step (ii), and/or        (b) the addition of the optional spacer chain extender, which        addition, following deprotection of the protected hydroxyl group        (A2″), produces a polymeric polyalcohol having reactive hydroxyl        groups (A2) for use in step (iii) or in a repeated step (iii)        and n dendritic branches which comprise one or more branching        generations, and at least one spacer generation is at least a        sub-generation.

Besides the hydroxyl-functional polyesters (A) that are essential to theinvention, the binder mixtures of the invention and the correspondingcoating compositions of the invention may if desired further compriseother hydroxyl-containing compounds (C). Other hydroxyl-containingcompounds (C) used may be not only low molecular weight polyols but alsooligomeric and/or polymeric polyols. Particular preference is given ascomponent (C) to non-component (A) polyester polyols, polyurethanepolyols, polysiloxane polyols, and, in particular, polyacrylate polyolsand/or polymethacrylate polyols, and also copolymers thereof. Theseoptional compounds (C) are used generally in an amount of 0% to 30% byweight, based on the total weight of the coating composition.

The Catalyst (D)

It is essential to the invention that the binder mixtures of theinvention and the coating compositions of the invention comprise atleast one phosphorus-containing and nitrogen-containing catalyst (D).Mixtures of two or more different catalysts (D) may also be used here.

Examples of suitable catalysts (D) are amine-blocked substitutedphosphonic diesters and amine-blocked diphosphonic diesters, preferablyfrom the group consisting of amine-blocked acyclic phosphonic diesters,amine-blocked cyclic phosphonic diesters, amine-blocked acyclicdiphosphonic diesters, and amine-blocked cyclic diphosphonic diesters.The corresponding nonblocked, phosphorus-containing catalysts aredescribed in German patent application DE-A-102005045228, for example.More particularly, however, use is made of amine-blocked substitutedphosphoric monoesters and phosphoric diesters, preferably from the groupconsisting of amine-blocked acyclic phosphoric diesters andamine-blocked cyclic phosphoric diesters. Blocking of thephosphorus-based catalysts with amines is necessary in order to be ableto ensure that the resulting formulations are stable on storage. Withsuitability for preparing the amine-blocked catalysts (D) used inaccordance with the invention, the acyclic phosphoric diesters (D) areselected more particularly from the group consisting of acyclicphosphoric diesters (D) of the general formula (II):

where the radicals R₁₀ and R₁₁ are selected from the group consistingof:

-   -   substituted and unsubstituted alkyl having 1 to 20, preferably 2        to 16, and more particularly 2 to 10 carbon atoms, cycloalkyl        having 3 to 20, preferably 3 to 16, and more particularly 3 to        10 carbon atoms, and aryl having 5 to 20, preferably 6 to 14,        and more particularly 6 to 10 carbon atoms,    -   substituted and unsubstituted alkylaryl, arylalkyl,        alkylcycloalkyl, cycloalkylalkyl, arylcycloalkyl,        cycloalkylaryl, alkylcycloalkylaryl, alkylarylcycloalkyl,        arylcycloalkylalkyl, arylalkylcycloalkyl, cycloalkylalkylaryl,        and cycloalkylarylalkyl, the alkyl, cycloalkyl, and aryl groups        present therein each containing the aforementioned number of        carbon atoms, and    -   substituted and unsubstituted radical of the aforementioned        kind, containing at least one, more particularly one, heteroatom        selected from the group consisting of oxygen atom, sulfur atom,        nitrogen atom, phosphorus atom, and silicon atom, more        particularly oxygen atom, sulfur atom, and nitrogen atom,        and being able additionally to be hydrogen as well (partial        esterification).

Particular preference is given to using as catalyst (D) amine-blockedphosphoric acid alkyl esters and phosphoric acid phenyl esters, verypreferably amine-blocked phosphoric acid phenyl esters.

In order to achieve the required electrical resistances of the coatingcomposition or of the binder mixture it is essential to the inventionthat the to catalyst (D) is blocked with one or more amines of theformula (I)

whereR₁ is an acyclic aliphatic or araliphatic hydrocarbon radical having atleast 3 C atoms,R₂ is an acyclic aliphatic or araliphatic hydrocarbon radical which isthe same or different from R₁ and/or R₃, andR₃ is hydrogen or an acyclic aliphatic or araliphatic hydrocarbonradical which is the same or different from R₁ and/or R₂.

Indeed, in aqueous solutions, catalysts based on phosphorus exhibit aparticularly high molar conductivity, more particularly the anions whenthey undergo condensation to form higher phosphates (diphosphates,triphosphates, and higher analogs), as described in David R. Lide, CRCHandbook of Chemistry and Physics, 73rd Edition, 1992-1993, p. 5-112.

The inventive combination of the stated catalysts with blocking agentscomprising at least one amine of the formula (I) leads surprisingly to amarked reduction in conductivity, i.e., to an increase in electricalresistance, even when the phosphorus-based catalysts (D) are used in aconcentration of at least 1% by weight, based on the nonvolatileconstituents of the binder mixture of the invention, as is necessary inorder to achieve the mechano-technological properties of the resultantcoatings.

In the formula (I) R₁ is an acyclic aliphatic or araliphatic hydrocarbonradical having at least 3 C atoms. R₂ is an acyclic aliphatic oraraliphatic hydrocarbon radical which is the same or different from R₁and/or R₃. R₁, R₂, and R₃ may contain not only purely aliphatic, acyclicstructures but to also aromatic structures. R₃ is hydrogen or is thesame as R₁ or is the same as R₂ or is an acyclic aliphatic oraraliphatic hydrocarbon radical other than R₁ and R₂. R₃ may likewisecontain not only purely aliphatic structures but also aromaticstructures.

It is preferred to use tertiary amines of the formula (I), since theyhave the advantage that they are unable to react with the otherconstituents of the coating composition, more particularly with theisocyanato-containing compounds (B).

It is preferred to use amines of the formula (I) in which at least oneof the radicals R₁, R₂ and R₃, preferably at least 2 of the radicals R₁,R₂, and R₃, are aliphatic hydrocarbon radicals having 6 to 18 C atoms,more preferably having 8 to 14 C atoms.

Use is made in particular of amines of the formula (I) in which at leastone of the radicals R₁, R₂, and R₃ is a branched aliphatic hydrocarbonradical. Particular preference is given to using amines of the formula(I) in which at least 2 of the radicals R₁, R₂, and R₃, and preferablyall 3 radicals R₁, R₂, and R₃, are branched aliphatic hydrocarbonradicals. It is especially preferred to use amines of the formula (I) inwhich at least one, more particularly two, and very preferably all ofthe radicals R₁, R₂, and R₃ are, branched aliphatic hydrocarbon radicalshaving at least 3 C atoms, preferably having 6 to 18 C atoms, morepreferably having 8 to 14 C atoms.

Through the use of amines of the formula (I) in which at least one ofthe radicals R₁, R₂, and R₃ is a branched aliphatic hydrocarbon radical,success is achieved in the provision of coating compositions which notonly ensure the required electrical resistances but also at the sametime prevent crystallization of the blocked catalyst. It will beappreciated that in accordance with the invention it is also possible toemploy those amines to of the formula (I) which lead to crystallizationof the blocked catalyst. This observed in particular for amines (I) inwhich either R₃ is hydrogen and R₁ and R₂ are linear aliphatichydrocarbon radicals or else all of the radicals R₁, R₂, and R₃ arelinear aliphatic hydrocarbon radicals. In that case it is usuallynecessary to add crystallization inhibitors in order to preventprecipitation of the blocked catalysts. The use of or search forsuitable crystallization inhibitors, however, may prove difficult.

It is also possible in accordance with the invention to block thecatalyst (D) not only exclusively with one amine of the formula (I) butalso to use, for the blocking of the catalysts (D) used in accordancewith the invention, a mixture of 2 different amines (I) or a mixture ofat least one amine of the formula (I) with at least one different amine.Thus, for example, mixtures of secondary or tertiary amines (I) withlinear radicals R₁, R₂ and/or R₃, and secondary or tertiary amines (I)with at least one branched radical, more particularly with amines (I) inwhich at least one of the radicals R₁, R₂, and R₃ is a branchedaliphatic hydrocarbon radical having 6 to 18 C atoms, preferably having8 to 14 C atoms, can be used. The use of suitable mixtures may likewiseprevent a possible crystallization. In that case the branched amine (I)thus acts as a crystallization inhibitor.

With particular preference the amine-blocked, phosphorus-containingcatalyst (D) comprises or the amine-blocked, phosphorus-containingcatalysts (D) comprise at least one tertiary amine of the formula (I)having a contour length of more than 8 pm as blocking agent.

The contour length is estimated by projecting the respective amine inits total extent, taking account of the respective hybridizations of theindividual atoms and the consequent bond angles, into a plane. Thisprojection is used in turn to project the maximum extent of therespective molecule onto a line. This is shown by way of example for theestimation of the contour length of pentylamine.

Since each of these projections is a vertical projection, the respectivecosine transformations are employed for the purpose of calculation:

Contribution Bond Projected to the length length contour Bond [pm]Number Alpha [pm] length [pm] C—C 154 4 30° 134 536 C—H 110 1 30° 95.395.3 N—C 101 1 30° 86.6 86.6

The bond lengths here are taken from the literature: see, for example,Marye A. Fox, James K. Whitesell: Organische Chemie. SpektrumAka-demischer Verlag, 1995, ISBN 3860252496. The overall contour lengthis a product of the sum of the individual contributions as per thetable. In this example, the contour length of pentylamine is found to be536 pm+95 pm+87 pm=718 pm.

Corresponding estimation of the contour lengths and of the resultinghydrodynamic volumes is based on the assumption of an average bondlength of 154 pm and also on a projected bond angle of 30° for thecorresponding organic bonds based on an sp3 hybridization. For furtherdetails, refer to the textbook by H. G. Elias, “Makromoleküle”, Hüthig &Wepf Verlag, Basel, Volume 1, “Grundlagen”, page 51.

Examples of suitable amines (I) with which the phosphoric esters areblocked are linear aliphatic amines such as trioctylamine, dioctylamine,octyldimethylamine, dinonylamine, trinonylamine, nonyldimethylamine,tridodecylamine, dodecyldimethylamine, and the like. Preference is givento using branched amines, such as di(isopropanol)amine, diisoamylamine,diisobutylamine, diisononylamine, and, in particular, branched tertiaryamines, examples being isododecyldimethylamine, tris(2-ethylhexyl)amine,triisoamylamine, triisononylamine, triisooctylamine, andtriisopropylamine, together if desired with linear aliphatic amines.

Especially preferred in accordance with the invention for use ascatalyst (D) are amine-blocked phosphoric acid phenyl esters, and moreparticularly phenyl phosphate blocked with tris(2-ethylhexyl)amine,dodecyldimethylamine and/or isododecyldimethylamine, very preferablywith tris(2-ethylhexyl)amine.

Certain amine-blocked phosphoric acid catalysts are also availablecommercially (e.g., Nacure products from King Industries).

The catalysts used are preferably in fractions of at least 1.0% byweight, preferably in fractions of 2.0% to 7.0% by weight, and morepreferably in fractions of 2.0% to 5.0% by weight, based on thenonvolatile constituents of the binder mixture of the invention. Arelatively low catalyst efficacy can be compensated in part by means ofcorrespondingly higher amounts employed.

In order to achieve a very balanced profile of properties it isgenerally worth aiming for as high as possible a concentration of theblocked catalyst. This has the advantage that the crosslinking of thesilane groups is very nearly complete and hence that a high networkdensity, and hence high scratch resistance and good chemical resistance,are achieved. Moreover, the risk of post-crosslinking events isespecially low when the conversion of the silane groups that is achievedis virtually complete immediately after the end of the curing operation.The upper limit on the amount of catalyst to be used is imposed by theelectrical resistance value, which may vary specifically, in accordancewith the mandate of the plant manufacturer.

The binder mixtures of the invention and/or the coating compositions ofthe invention may also comprise a further amine catalyst based on abicyclic amine, more particularly on an unsaturated bicyclic amine.Examples of suitable amine catalysts are1,5-diazabicyclo[4.3.0]non-5-ene or 1,8-diazabicyclo[5.4.0]undec-7-ene.

These amine catalysts are used preferably in fractions of 0.01% to 20%by weight, more preferably in fractions of 0.1% to 10% by weight, basedon the nonvolatile constituents of the binder mixture of the invention.

Further Components of the Binder Mixture

The binder mixture typically further comprises at least one organicsolvent. Particularly suitable solvents for the binder mixture of theinvention are those which in the binder mixture and in the coatingcomposition are chemically inert toward the compounds (A), (B), and,where used, (C), and which also do not react with (A) and (B) when thecoating composition is being cured. Examples of such solvents arealiphatic and/or aromatic is hydrocarbons such as toluene, xylene,solvent naphtha, Solvesso 100 or Hydrosol® (ARAL), ketones, such asacetone, methyl ethyl ketone or methyl amyl ketone, esters, such asethyl acetate, butyl acetate, pentyl acetate or ethyl ethoxypropionate,ethers, or mixtures of the aforementioned solvents. The aprotic solventsor solvent mixtures preferably have a water content of not more than 1%by weight, more preferably not more than 0.5% by weight, based on thesolvent. In order to ensure good appearance, a high fraction of butylacetate as solvent is employed in particular, more preferably at least60% by weight of butyl acetate, based on the total weight of the solventmixture. Further solvents are employed in order to bring about thecorrespondingly desired evaporation numbers.

The solids content of the binder mixture of the invention isadvantageously at least 50%, preferably at least 70%, by weight.

The binder mixture of the invention, lastly, may further comprise one ormore of the typical, known coatings additives (F) described below.

The Coating Compositions of the Invention The Isocyanato-ContainingCompounds (B)

The coating compositions of the invention, in addition to theabove-described binder mixture of the invention, comprise at least onesaturated compound (B) having isocyanate groups, which contains at leastin part hydrolyzable silane groups.

The di- and/or polyisocyanates which serve as core structures for theisocyanato-containing compounds (B) used preferably in accordance withthe invention are preferably conventional saturated, substituted orunsubstituted, aromatic, aliphatic, cycloaliphatic and/or heterocyclicpolyisocyanates. Examples of preferred polyisocyanates are as follows:2,4-toluene diisocyanate, 2,6-toluene diisocyanate, diphenylmethane4,4′-diisocyanate, diphenylmethane 2,4′-diisocyanate, p-phenylenediisocyanate, biphenyl diisocyanates, 3,3′-dimethyl-4,4′-diphenylenediisocyanate, tetramethylene 1,4-diisocyanate, hexamethylene1,6-diisocyanate, 2,2,4-trimethylhexane 1,6-diisocyanate, isophoronediisocyanate, ethylene diisocyanate, 1,12-dodecane diisocyanate,cyclobutane 1,3-diisocyanate, cyclohexane 1,3-diisocyanate, cyclohexane1,4-diisocyanate, methylcyclohexyl diisocyanates, hexahydrotoluene2,4-diisocyanate, hexahydrotoluene 2,6-diisocyanate, hexahydrophenylene1,3-diisocyanate, hexahydrophenylene 1,4-diisocyanate,perhydrodi-phenylmethane 2,4′-diisocyanate, 4,4′-methylenedicyclohexyldiisocyanate (e.g., Desmodur® W from Bayer AG), tetramethylxylyldiisocyanates (e.g., TMXDI® from American Cyanamid), and mixtures of theaforementioned polyisocyanates. Further-preferred polyisocyanates arethe biuret dimers and the isocyanurate trimers of the aforementioneddiisocyanates. Particularly preferred polyisocyanates PI arehexamethylene 1,6-diiso-cyanate, isophorone diisocyanate, and4,4′-methylenedicyclohexyl diisocyanate, their biuret dimers and/orisocyanurate trimers.

In a further embodiment of the invention the polyisocyanates arepolyisocyanate prepolymers with urethane structural units, which areobtained by reacting polyols with a stoichiometric excess ofaforementioned polyisocyanates. Polyisocyanate prepolymers of this kindare described in U.S. Pat. No. 4,598,131, for example.

It is essential to the invention that the isocyanato-containing compound(B) contains at least in part hydrolyzable silane groups. Thesehydrolyzable silane groups lead to the construction of the Si—O—Sinetwork to which is distributed statistically in the finally curedcoating. This means that there is no deliberate accumulation ordepletion of the Si—O—Si network in particular regions of the coating.

It is preferred if the compound (B) comprises

between 2.5 and 97.5 mol %, based on the entirety of structural units(III) and (IV), of at least one structural unit of the formula (III)

—N(X—SiR″x(OR′)3-x)n(X′—SiR″y(OR′)3-y)m  (III)

whereR′=hydrogen, alkyl or cycloalkyl, it being possible for the carbon chainto be interrupted by nonadjacent oxygen, sulfur or NRa groups, withRa=alkyl, cycloalkyl, aryl or aralkyl, preferably R′=ethyl and/or methylX, X′=linear and/or branched alkylene or cycloalkylene radical having 1to 20 carbon atoms, preferably X, X′=alkylene radical having 1 to 4carbon atomsR″=alkyl, cycloalkyl, aryl, or aralkyl, it being possible for the carbonchain to be interrupted by nonadjacent oxygen, sulfur or NRa groups,with Ra=alkyl, cycloalkyl, aryl or aralkyl, preferably R″=alkyl radical,in particular having 1 to 6 C atoms,n=0 to 2, m=0 to 2, m+n=2, and x, y=0 to 2,andbetween 2.5 and 97.5 mol %, based on the entirety of structural units(III) and (IV), of at least one structural unit of the formula (IV)

—Z—(X—SiR″x(OR′)3-x)  (IV),

whereZ=—NH—, —NR—, withR=alkyl, cycloalkyl, aryl or aralkyl, it being possible for the carbonchain to be interrupted by nonadjacent oxygen, sulfur or NRa groups,with Ra=alkyl, cycloalkyl, aryl or aralkyl,x=0 to 2, andX, R′, R″ have the definition stated in the case of formula (III).

The respective preferred alkoxy radicals (OR′) may be alike ordifferent; critical for the structure of the radicals, however, is theextent to which they influence the reactivity of the hydrolyzable silanegroups. Preferably R′ is an alkyl radical, more particularly having 1 to6 C atoms. Particular preference is given to radicals R′ which increasethe reactivity of the silane groups, i.e., which represent good leavinggroups. With that aim in mind, a methoxy radical is preferred over anethoxy radical, which is preferred in turn over a propoxy radical. Withparticular preference, therefore, R′=ethyl and/or methyl, moreparticularly methyl.

Furthermore, the reactivity of organofunctional silanes may also beinfluenced considerably by the length of the spacers X between silanefunctionality and organic functional group that serves for reaction withthe modifying constituent. As examples of this, mention may be made ofthe “alpha” silanes available from Wacker, in which a methylene group isbetween the Si atom and the functional group, rather than the propylenegroup that is present in the case of “gamma” silanes.

The isocyanato-containing compounds (B) functionalized with thestructural units (III) and (IV) that are particularly preferred inaccordance with the invention are obtained with particular preference byreaction of the aforementioned di- and/or polyisocyanates with acompound of the formula (IIIa)

HN(X—SiR″x(OR′)3-x)n(X′—SiR″y(OR′)3-y)m  (IIIa),

and with a compound of the formula (IVa)

H—Z—(X—SiR″x(OR′)3-x)  (IVa),

the substituents having the definition stated above.

Compounds (IIIa) preferred in accordance with the invention arebis(2-ethyltrimethoxysilyl)amine, bis(3-propyltrimethoxysilyl)amine,bis(4-butyltrimethoxysilyl)amine, bis(2-ethyltriethoxysilyl)amine,bis(3-propyltriethoxysilyl)amine and/or bis(4-butyltriethoxysilyl)amine.Bis(3-propyltrimethoxysilyl)amine is especially preferred. Aminosilanesof this kind are available, for example, under the brand name DYNASYLAN®from DEGUSSA or Silquest® from OSI.

Compounds (IVa) that are preferred in accordance with the invention areaminoalkyltrialkoxysilanes, such as, preferably,2-aminoethyltrimethoxy-silane, 2-aminoethyltriethoxysilane,3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane,4-aminobutyltrimethoxysilane, 4-aminobutyl-triethoxysilane. Particularlypreferred compounds (IVa) are N-(2-(trimethoxysilyl)ethyl)alkylamines,N-(3-(trimethoxysilyl)propyl)alkylamines,N-(4-(trimethoxysilyl)butyl)alkylamines,N-(2-(triethoxysilyl)ethyl)alkyl-amines,N-(3-(triethoxysilyl)propyl)alkylamines and/orN-(4-(triethoxysilyl)-butyl)alkylamines. N-(3-(Trimethoxysilyl)propyl)butylamine is especially preferred. Aminosilanes of this kind areavailable, for example, under the brand name DYNASYLAN® from DEGUSSA orSilquest® from OSI.

The isocyanato-containing compounds (B) functionalized with thestructural units (III) and (IV) that are especially preferred inaccordance with the invention are prepared with particular preference byreaction of the aforementioned di- and/or polyisocyanates with theaforementioned compounds (IIIa) and (IVa), with reaction of between 2.5and 90 mol %, preferably 5 to 85 mol %, more preferably 7.5 to 80 mol %,of the isocyanate groups in the core polyisocyanate structure with atleast one compound (IIIa) and between 2.5 and 90 mol %, preferably 5 to85 mol %, more preferably 7.5 to 80 mol %, of the isocyanate groups inthe core polyisocyanate structure with at least one compound (IVa).

The total fraction of the isocyanate groups reacted with the compounds(IIIa) and (IVa) in the polyisocyanate compound (B) is between 5 and 95mol %, preferably between 10 and 90 mol %, more preferably between 15and 85 mol % of the isocyanate groups in the core polyisocyanatestructure.

Especially preferred isocyanato-containing compounds (B) are reactionproducts of hexamethylene 1,6-diisocyanate and/or isophoronediisocyanate, and/or isocyanurate trimers thereof, withbis(3-propyltrimethoxysilyl)amine andN-(3-(trimethoxysilyl)propyl)butylamine.

The solids content of the polyisocyanate curing agent (B) used inaccordance with the invention is advantageously at least 50% by weight,preferably at least 70% by weight.

The polyisocyanate curing agent used in accordance with the inventionpreferably comprises at least one water scavenger, examples beingreactive silanes having a higher reactivity toward water than doisocyanates. As water scavengers it is advantageous in particular to usetrialkyl esters of orthoformic acid. A particularly preferred waterscavenger used is triethyl orthoformate. Preference is given to adding0.01% to 10% by weight, preferably 0.03% to 5.0% by weight, of at leastone water scavenger, based on the total amount of nonvolatiles in thecoating composition.

The reaction of the isocyanato-containing compounds (B) with thecompounds (IIIa) and (IVa) takes place preferably in an inert gasatmosphere at temperatures of not more than 100° C., preferably of notmore than 60° C. The reaction of the isocyanato-containing compounds (B)with the compounds (IIIa) and (IVa) takes place preferably in a solventor is in a solvent mixture in the presence of at least one waterscavenger and in the presence of at least one amine, preferably in thepresence of at least one tertiary amine, such as, for example,1,4-diazabicyclo[2.2.2]octane (DABCO), triethylamine anddiisopropylethylamine, especially triethylamine.

Preferably, during the synthesis, at least 1%, preferably at least 2%,more preferably at least 3%, and very preferably at least 4% by weightof at least one water scavenger, preferably triethyl orthoformate, isadded, based on the total amount of nonvolatiles in the reactionmixture.

Preferably the amine is used during the synthesis in an amount of 2% to6% by weight, based on the total amount of nonvolatiles in the reactionmixture. Particular preference is given to using triethylamine duringthe synthesis in an amount of 1.5% to 3.5% by weight, based on the totalamount of nonvolatiles in the reaction mixture.

The solvent or solvent mixture in which the polyisocyanate curing agentsare prepared may be composed of aromatic hydrocarbons such as1,2,4-trimethylbenzene, mesitylene, xylene, propylbenzene andisopropylbenzene. One example of a suitable solvent mixture comprisingaromatic hydrocarbons is solvent naphtha. The solvent in which thepolyisocyanate curing agents are prepared may also be composed ofaliphatic hydrocarbons, ketones, such as acetone, methyl ethyl ketone ormethyl amyl ketone, esters, such as ethyl acetate, butyl acetate, pentylacetate or ethyl ethoxy propionate, ethers or mixtures of theaforementioned solvents, preference being given to solvent mixtures tohaving a high butyl acetate fraction, more particularly at least 60% byweight of butyl acetate, based on the total weight of the solventmixture. With particular preference the solvent mixture contains atleast 80% by weight of butyl acetate, more particularly at least 95% byweight of butyl acetate. Very particular advantage attaches to workingin pure butyl is acetate.

Alternatively the polyisocyanate curing agent can also be preparedpreferably by reacting in a first step on average per molecule not morethan one of the isocyanate groups of the polyisocyanate with theamino-functional alkoxysilane and in a second step reacting theresulting intermediate by dimerization, trimerization, urethanization,biuretization or allophanatization to form a polyisocyanate.

The free isocyanate groups of the isocyanato-containing compounds B canalso be used in a blocked form. This is preferably the case when thecoating compositions of the invention are used as one-component systems.For the blocking it is possible in principle to use any blocking agentwhich can be used for the blocking of polyisocyanates and has asufficiently low deblocking temperature. Such blocking agents are veryfamiliar to the skilled worker. Preference is given to using blockingagents of the kind described in EP-A-0 626 888 and EP-A-0 692 007.

The Combination of Components A, B, Optionally C, and D and FurtherComponents of the Coating Composition

The weight fraction of the hydroxyl-containing polyesters (A) to beemployed, based on the weight fraction of the isocyanato-containingcompounds (B), is dependent on the hydroxyl equivalent weight of thepolyester and on the equivalent weight of the free isocyanate groups ofthe polyisocyanate.

In the coating composition of the invention there is preferably 2.5 to97.5 mol %, based on the sum of structural units (III) and (IV), ofstructural units (III) and 2.5 to 97.5 mol %, based on the sum ofstructural units (III) and (IV), of structural units (III).

The coating compositions of the invention contain preferably between2.5% and 97.5%, more preferably between 5% and 95%, very preferablybetween 10% and 90%, and in particular between 20% and 80%, by weight,based on the amount of nonvolatile substances in the coatingcomposition, of the hydroxyl-containing polyester (A), and preferablybetween 2.5% and 97.5%, more preferably between 5% and 95%, verypreferably between 10% and 90%, and in particular between 20% and 80%,by weight, based on the amount of nonvolatile substances in the coatingcomposition, of the isocyanato-containing compounds (B).

Based on the sum of the functional groups critical for crosslinking inthe coating composition of the invention, formed from the fractions ofthe hydroxyl and isocyanate groups and also the fractions of thestructural elements (III) and (IV), the structural elements (III) and(IV) are present preferably in fractions of 2.5 to 97.5 mol %, morepreferably between 5 and 95 mol %, and very preferably between 10 and 90mol %.

In order to ensure further-improved resistance properties on the part ofthe coatings of the invention toward cracking under UV radiation andwet/dry cycling in the CAM180 test (to DIN EN ISO 11341 Feb 98 and DINEN ISO 4892-2 Nov 00) in combination with a high scratch resistancedirectly following the thermal cure, a high gloss, and high glossretention after weathering, it is additionally preferred to select thelevel of structural units (III) and/or (IV) to be at most such that thecoating compositions of the invention contain less than 6.5% by mass ofSi of the structural units (III) and/or (IV), very preferably not morethan 6.0% by mass of Si of the structural units (III) and/or (IV), basedin each case on the solids content to of the coating compositions. Thesilane content in % by mass of Si is determined arithmetically from theamounts of the compounds (IIIa) and (IVa) that are used.

The weight fractions of the polyester (A), of the compound (C), if used,and of the polyisocyanate (B) are preferably selected such that themolar equivalent ratio of the unreacted isocyanate groups of theisocyanato-containing compounds (B) to the hydroxyl groups of thepolyester (A) and the optionally used compound (C) is between 0.9:1.0and 1.2:1.0, preferably between 0.95:1.0 and 1.1:1.0, more preferablybetween 0.98:1.0 and 1.05:1.0.

Where the compositions are one-component coating compositions, aselection is made of the isocyanato-containing compounds (B) whose freeisocyanate groups have been blocked with the blocking agents describedabove.

In the case of the inventively preferred 2-component (2K) coatingcompositions, the binder mixture comprising the hydroxyl-containingpolyester (A), optionally (C), the catalyst (D), a portion of thesolvent, and also, if desired further components, described below, ismixed conventionally with a further coating component, comprising theisocyanato-containing compound (B) and, where appropriate, further ofthe components described below, this mixing taking place shortly beforethe coating composition is applied.

Solvents suitable for the coating compositions of the invention are inparticular those which, in the coating composition, are chemically inerttoward the compounds (A), (B), and, if used, (C) and also do not reactwith (A) and (B) when the coating composition is being cured. Examplesof such solvents are aliphatic and/or aromatic hydrocarbons such astoluene, xylene, solvent naphtha, Solvesso 100 or Hydrosol® (from ARAL),ketones, such as acetone, methyl ethyl ketone or methyl amyl ketone,esters, such as ethyl acetate, butyl acetate, pentyl acetate or ethylethoxypropionate, ethers, or mixtures of the aforementioned solvents.The aprotic solvents or solvent mixtures preferably have a water contentof not more than 1%, more preferably not more than 0.5%, by weight,based on is the solvent. In order to ensure a good appearance, use ismade in particular of a high fraction of butyl acetate as solvent, morepreferably at least 60% by weight of butyl acetate, based on the totalweight of the solvent mixture. Further solvents are employed in order tobring about the correspondingly desired evaporation numbers.

Besides the compounds (A), (B), and (C) it is possible additionally touse further binders (E), which preferably are able to react and formnetwork points with the hydroxyl groups of the polyester (A) and/or withthe free isocyanate groups of the compound (B) and/or with thealkoxysilyl groups of the compounds (B) and/or (C).

By way of example it is possible to use amino resins and/or epoxy resinsas component (E). Suitable amino resins are the typical, known aminoresins, some of whose methylol and/or methoxymethyl groups may have beendefunctionalized by means of carbamate or allophanate groups.Crosslinking agents of this kind are described in patents U.S. Pat. No.4,710,542 and EP-B-0 245 700 and also in the article by B. Singh andcoworkers, “Carbamylmethylated Melamines, Novel Crosslinkers for theCoatings Industry”, in Advanced Organic Coatings Science and TechnologySeries, 1991, volume 13, pages 193 to 207.

Generally speaking, such components (E) are used in fractions of up to40%, preferably up to 30%, more preferably up to 25%, by weight, basedon the nonvolatile constituents of the coating composition.

The binder mixture or coating composition of the invention may furthercomprise at least one typical, known coatings additive (F) in effectiveamounts, i.e., in amounts preferably up to 30%, more preferably up to25%, and in particular up to 20% by weight, in each case based on thenonvolatile constituents of the coating composition.

Examples of suitable coatings additives (F) are:

-   -   particularly UV absorbers;    -   particularly light stabilizers such as HALS compounds,        benzotriazoles or oxalanilides;    -   free-radical scavengers;    -   slip additives;    -   polymerization inhibitors;    -   defoamers;    -   reactive diluents, of the kind which are common knowledge from        the prior art, and which are preferably inert toward the        —Si(OR)3 groups;    -   wetting agents such as siloxanes, fluorine compounds, carboxylic        monoesters, phosphoric esters, polyacrylic acids and their        copolymers, or polyurethanes;    -   adhesion promoters such as tricyclodecanedimethanol;    -   flow control agents;    -   film-forming assistants such as cellulose derivatives;    -   fillers such as, for example, nanoparticles based on silicon        dioxide, aluminum oxide or zirconium oxide; for further details        refer to Römpp Lexikon “Lacke and Druckfarben” Georg Thieme        Verlag, Stuttgart, 1998, pages 250 to 252;    -   rheology control additives, such as the additives known from        patents WO 94/22968, EP-A-0 276 501, EP-A-0 249 201 or WO        97/12945; crosslinked polymeric microparticles, as disclosed for        example in EP-A-0 008 127; inorganic phyllosilicates such as        aluminum-magnesium silicates, sodium-magnesium and        sodium-magnesium-fluorine-lithium phyllosilicates of the        montmorillonite type; silicas such as Aerosils®; or synthetic        polymers containing ionic and/or associative groups such as        polyvinyl alcohol, poly(meth)acrylamide, poly(meth)acrylic acid,        polyvinylpyrrolidone, styrene-maleic anhydride copolymers or        ethylene-maleic anhydride copolymers and their derivatives, or        hydrophobically modified ethoxylated urethanes or polyacrylates;    -   flame retardants, and/or    -   the crystallization inhibitors and/or water scavengers already        listed above.

In particular, light stabilizers based on sterically hindered amines(HALS), light stabilizers based on UV absorbers, such as benzotriazolesor oxalanilides, and also rheological assistants, may likewiseunfavorably influence, i.e., lower, the electrical resistance of thecoating component or coating composition comprising them, andconsequently the amounts in which they are used ought not to be selectedtoo highly. On the other hand, however, these additives are also usedwith preference in certain minimum amounts in order to ensure thedesired mechano-technological properties of the coating compositions andcoatings. The amounts employed, however, can be determined easily by theskilled worker on the basis of a few routine tests.

Preference is therefore given to binder mixtures and coatingcompositions which comprise at least one light stabilizer based onsterically hindered amines (HALS), particular preference being given tobinder mixtures and coating compositions which comprise at least onelight stabilizer based on sterically hindered amines (HALS) in aconcentration of more than 0.5% by weight up to a maximum of 3.0% byweight, based in each case on the nonvolatile constituents of thecoating composition.

Preference is likewise given to binder mixtures and coating compositionswhich comprise at least one UV absorber, particular preference beinggiven to binder mixtures and coating compositions which comprise atleast one UV absorber in a concentration of more than 0.5% by weight upto a maximum of 3.0% by weight, based in each case on the nonvolatileconstituents of the coating composition.

Particularly preferred binder mixtures and coating compositions compriseat least one light stabilizer based on sterically hindered amines (HALS)and at least one UV absorber.

Preference is likewise given to binder mixtures and coating compositionswhich comprise at least one rheological assistant, more preferably in aconcentration of more than 2% by weight up to a maximum of 10% byweight, based in each case on the nonvolatile constituents of thecoating composition.

In a further embodiment of the invention the binder mixture or coatingcomposition of the invention may additionally comprise further pigmentsand/or fillers and may serve for producing pigmented topcoats. Thepigments and/or fillers employed for this purpose are known to theskilled worker.

Because the coatings of the invention produced from the coatingcompositions of the invention adhere excellently even to electrocoats,surface coats, basecoat systems or typical, known clearcoat systems thathave already cured, they are outstandingly suitable not only for use inautomotive OEM finishing but also for automotive refinish or for themodular scratchproofing of automobile bodies that have already beenpainted.

The coating compositions of the invention can be applied by any of thetypical application methods, such as spraying, knife coating, spreading,pouring, dipping, impregnating, trickling or rolling, for example. Inthe course of such application, the substrate to be coated may itself beat rest, with the application equipment or unit being moved.Alternatively the substrate to be coated, in particular a coil, may bemoved, with the application unit at rest relative to the substrate orbeing moved appropriately.

Preference is given to employing spray application methods, such ascompressed-air spraying, airless spraying, high-speed rotation,electrostatic spray application (ESTA), alone or in conjunction with hotspray application such as hot-air spraying, for example.

The applied coating compositions of the invention can be cured after acertain rest time. The rest time serves, for example, for the levelingand devolatilization of the coating films or for the evaporation ofvolatile constituents such as solvents. The rest time may be assistedand/or shortened by the application of elevated temperatures and/or by areduced humidity, provided this does not entail any damage or alterationto the coating films, such as premature complete crosslinking, forinstance.

The thermal curing of the coating compositions has no peculiarities interms of method but instead takes place in accordance with the typical,known methods such as heating in a forced-air oven or irradiation withIR lamps. The thermal cure may also take place in stages. Anotherpreferred curing method is that of curing with near infrared (NIR)radiation.

The thermal cure takes place advantageously at a temperature of 30 to200° C., more preferably 40 to 190° C., and in particular 50 to 180° C.for a time of 1 min up to 10 h, more preferably 2 min up to 5 h, and inparticular 3 min to 3 h, although longer cure times may be employed inthe case of the temperatures that are employed for automotive refinish,which are preferably between 30 and 90° C.

The coating compositions of the invention produce new cured coatings,especially coating systems, more particularly clearcoat systems;moldings, especially optical moldings; and self-supporting films, all ofwhich are highly scratchproof and in particular are stable to chemicalsand to weathering, and have a very good overall appearance. The coatingsand coating systems of the invention, especially the clearcoat systems,can in particular be produced even in film thicknesses >40 μm withoutstress cracks occurring.

For these reasons the coating compositions of the invention are ofexcellent suitability as decorative, protective and/or effect-imparting,highly scratchproof coatings and coating systems on bodies of means oftransport (especially motor vehicles, such as motorcycles, buses, trucksor automobiles) or parts thereof; on buildings, both interior andexterior; on furniture, windows, and doors; on plastics moldings,especially CDs and windows; on small industrial parts, on coils,containers, and packaging; on white goods; on films; on optical,electrical, and mechanical components; and on hollow glassware andarticles of everyday use.

The coating compositions and coating systems of the invention,especially the clearcoat systems, are employed in particular in thetechnologically and esthetically particularly demanding field ofautomotive OEM finishing and also of automotive refinish. Withparticular preference the coating compositions of the invention are usedin multistage coating methods, particularly in methods where a pigmentedbasecoat film is first applied to an uncoated or precoated substrate andthereafter a film with the coating compositions of the invention isapplied. The invention, accordingly, also provides multicoat effectand/or color coating systems comprising at least one pigmented basecoatfilm and at least one clearcoat disposed thereon, wherein the clearcoathas been produced from the coating composition of the invention.

Not only water-thinnable basecoat materials but also basecoat materialsbased on organic solvents can be used. Suitable basecoat materials aredescribed for example in EP-A-0 692 007 and in the documents cited therein column 3 lines 50 et seq. The applied basecoat material is ispreferably first dried, i.e., at least some of the organic solventand/or water is stripped from the basecoat film in an evaporation phase.Drying is accomplished preferably at temperatures from room temperatureto 80° C. Drying is followed by the application of the coatingcomposition of the invention. Subsequently the two-coat system is baked,preferably under conditions employed for automotive OEM finishing, attemperatures from 30 to 200° C., more preferably 40 to 190° C., and inparticular 50 to 180° C., for a time of 1 min up to 10 h, morepreferably 2 min up to 5 h, and in particular 3 min to 3 h, althoughlonger cure times may also be employed at the temperatures employed forautomotive refinish, which are preferably between 30 and 90° C.

The coats produced with the coating composition of the invention arenotable in particular for an especially high chemical stability andweathering stability and also for a very good carwash resistance andscratch resistance, and at the same time exhibit very good overallappearance.

In a further preferred embodiment of the invention, the coatingcomposition of the invention is used as a transparent clearcoat materialfor coating plastics substrates, especially transparent plasticssubstrates. In this case the coating compositions include UV absorbers,which in terms of amount and type are also designed for effective UVprotection of the plastics substrate. Here as well, the coatingcompositions are notable for an outstanding combination ofscratchproofing and weathering stability with at the same time very goodappearance. The plastics substrates thus coated are used preferably as asubstitute for glass components in to automobile construction, theplastics substrates being composed preferably of polymethyl methacrylateor polycarbonate.

EXAMPLES Preparation of the Inventive Polyester Polyol A1

In a reactor provided with a stirrer, reflux condenser, and waterseparator, 1215.4 parts by weight of isononanoic acid are introduced and140 parts by weight of xylene are added. The mixture is heatedcautiously with stirring to 80° C. Then 2284.6 parts by weight of adendritic hydroxyl-functional polyester (Boltorn H 30, available fromPerstorp) are added slowly in order to prevent lumps forming. Followingthe addition the reaction mixture is heated to 200° C. For monitoringthe course of the reaction, the volume of condensate is recorded andfrom time to time a sample is taken for determination of the hydroxylnumber. When the amount of condensate calculated beforehand ascorresponding to complete conversion has been reached, the xylenefraction is removed by distillation. The reaction mixture is stirred at200° C. until an acid number of less than 5 mg KOH/g (determined inaccordance with DIN 53402) is reached. The mixture is cooled to 145° C.and dissolved in 840 parts by weight of butyl acetate.

The resulting polyester resin has a solids fraction of 78.8% by weight.The resulting hydroxyl number is 190 mg KOH/g (determined in accordancewith DIN 53240), the acid number 5.8 mg KOH/g (DIN 53402).

Preparation of the Inventively Blocked, Phosphorus-Based Catalyst (D1)(Blocking Agent Tris(2-Ethylhexyl)Amine)

A 1000 ml glass flask is charged with 226.34 g of butyl acetate and94.65 g of phenyl phosphate (75% strength, in butanol, available fromIsle Chem). The mixture is stirred at room temperature and homogenized.Subsequently 179.02 g of tris(2-ethylhexyl)amine (available from BASFSE) are added slowly dropwise at a rate such that 60° C. are notexceeded. After the end of the addition, the product is stirred at 40°C. for a further 3 h.

Preparation of the Inventively Blocked, Phosphorus-Based Catalyst (D2)(Blocking Agent Diisopropanolamine)

A 1000 ml glass flask is charged with 211.90 g of butyl acetate and187.00 g of phenyl phosphate (75% strength, in butanol, available fromIsle Chem). The mixture is stirred at room temperature and homogenized.Subsequently 148.00 g of diisopropanolamine (DIPA, BASF SE) are addedslowly dropwise at a rate such that 60° C. are not exceeded. After theend of the addition, the product is stirred at 40° C. for a further 3 h.

Preparation of the Inventively Blocked, Phosphorus-Based Catalyst (D3)(Blocking Agent Dimethyldodecylamine)

A 500 ml glass flask is charged with 42.00 g of butyl acetate and 32.00g of phenyl phosphate (75% strength, in butanol, available from IsleChem). The mixture is stirred at room temperature and homogenized.Subsequently 26.00 g of dimethyldodecylamine (DDA, ABCR, Karlsruhe) areadded slowly dropwise at a rate such that 60° C. are not exceeded. Afterthe end of the addition, the product is stirred at 40° C. for a further3 h.

Preparation of a Noninventively Blocked, Phosphorus-Based Catalyst (DC1)(Blocking Agent DBU)

A 500 ml glass flask is charged with 53.25 g of hexanol and 17.75 g ofbutyl acetate and 16.0 g of phenyl phosphate (75% strength, in butanol,available from Isle Chem). The mixture is stirred at room temperatureand homogenized. Subsequently 13.0 g of Lupragen N 700(1,8-diazabicyclo-[5.4.0]undec-7-ene (DBU, BASF SE) are added slowlydropwise at a rate such that 60° C. are not exceeded. After the end ofthe addition, the product is stirred at 40° C. for a further 3 h.

Preparation of a Noninventively Blocked, Phosphorus-Based Catalyst (DC2)(Blocking Agent DMEA)

A 1000 ml glass flask is charged with 195.2 g of butyl acetate and 219.1g of phenyl phosphate (75% strength, in butanol, available from IsleChem). The mixture is stirred at room temperature and homogenized.Subsequently 85.7 g of dimethylethanolamine (DMEA, BASF SE) are addedslowly dropwise at a rate such that 60° C. are not exceeded. After theend of the addition, the product is stirred at 40° C. for a further 3 h.

Preparation of a Noninventively Blocked, Phosphorus-Based Catalyst (DC3)(Blocking Agent Morpholine)

A 1000 ml glass flask is charged with 198.6 g of butyl acetate and 205.6g of phenyl phosphate (75% strength, in butanol, available from IsleChem). The mixture is stirred at room temperature and homogenized.Subsequently 95.8 g of morpholine (BASF SE) are added slowly dropwise ata rate such that 60° C. are not exceeded. After the end of the addition,the product is stirred at 40° C. for a further 3 h.

The solution thus obtained was initially stable on storage. After 4weeks, however, the material underwent crystallization and could be usedagain as pure substance only after brief heating to 60° C. and completedissolution of the crystals.

Preparation of a Rheological Assistant F1 Based on Ureas

A 5 l Juvo reaction vessel with heating mantle, thermometer, stirrer,and top-mounted condenser was charged with 875.7 g of an aromaticsolvent. With stirring and under an inert gas atmosphere (200 cm3/minnitrogen), the aromatic solvent was heated to 160° C. undersuperatmospheric pressure (max. 3.5 bar). Using a measuring pump, amixture of 37.5 g of di-tert-butyl peroxide and 138.6 g of an aromaticsolvent was added dropwise at a uniform rate over the course of 4.75 h.0.25 h after the beginning of the addition, a measuring pump was used toadd 848.4 g of styrene, 600.0 g of n-butyl acrylate, 418.2 g ofhydroxyethyl acrylate, and 38.4 g of methacrylic acid at a uniform rateover the course of 4 h. After the end of the addition, the temperaturewas maintained for 2 h and then the product was cooled to 60° C. andfiltered through a 5 μm GAF bag. The resulting resin had an acid numberof 15 mg KOH/g (to DIN 53402), a solids content of 65%+/−1 (60 min, 130°C.), and a viscosity of 8.5 dPa*s according to the experimentalspecification of DIN ISO 2884-1 (55% in solvent naphtha).

A 1 l reactor was charged with 423.5 g of the resin solution and thisinitial charge was diluted with 29.4 g of butyl acetate. Thereafter 11.2g of benzylamine were added and the mixture was stirred for 30 min.After this time, with application of high shearing forces, a mixture of8.8 g of hexamethylene diisocyanate and 17.1 g of butyl acetate wasadded in such a way that a reaction temperature of 40° C. was notexceeded. The resulting mixture had a viscosity of >800 mPas (10 s-1)(Z3) (DIN ISO 2884-1) and a solids content of 59.0% (60 min, 130° C.).

Preparation of the Inventive Partly Silanized Polyisocyanate B1 (HDIwith 10 mol % IVa and 90 Mol % IIIa, Degree of Conversion of theIsocyanate Groups=30 mol %)

A round-bottom flask with a reflux condenser was charged with 36.296parts by weight of trimerized hexamethylene diisocyanate (commercialproduct Basonat HI 100 from BASF SE, Ludwigshafen), 36.093 parts byweight of butyl acetate, and 2.458 parts by weight of triethylorthoformate. 1.786 parts by weight ofN-(3-trimethoxysilylpropan-1-yl)-N-n-butylamine (commercial productDynasylan 1189 from Evonik) and 23.367 parts by weight ofN,N-bis(3-trimethoxysilylpropan-1-yl)amine (commercial product Dynasylan1124 from Evonik) were premixed and metered in slowly at roomtemperature, under reflux and with nitrogen blanketing, in such a waythat the product temperature did not exceed 60° C. Subsequently thereaction mixture was heated to 60° C. and held until the residual NCOcontent had reached 4.9% (NCO determination by titration).

The electrical resistance of the silanized isocyanate B1 thus preparedwas measured by means of a dip probe measuring cell with an LC 2conductivity meter from Byk Gardner (in accordance with DIN 55667), andwas found to be 1080 kohm. The result is therefore well above therequired figure of 200 kohm.

Formulation of the Binder Mixtures

The binder mixtures of inventive examples 1 to 4 and also the bindermixtures of comparative examples 1 to 4 were prepared from thecomponents indicated in table 1, by mixing.

TABLE 1 Composition of the binder mixtures in parts by weight Invent.Comp. ex. 1 Comp. ex. 2 Comp. ex. 3 Comp. ex. 4 ex. 1 Invent. ex. 2Invent. ex. 3 Invent. ex. 4 Polyester A1 36.6 36.6 36.6 36.6 36.6 36.636.6 36.6 Additive F1 21.0 21.0 21.0 21.0 21.0 21.0 21.0 21.0 Butylacetate 14.7 14.7 14.7 14.7 14.7 14.7 14.7 14.7 Butylglycol 2.1 2.1 2.12.1 2.1 2.1 2.1 2.1 diacetate Triethyl ortho- 2.1 2.1 2.1 2.1 2.1 2.12.1 2.1 formate Dynoadd¹⁾ 0.20 0.20 0.20 0.20 0.20 0.20 0.20 0.20Tin.384²⁾ 1.60 1.60 1.60 1.60 1.60 1.60 1.60 1.60 Tin.152³⁾ 2.75 2.752.75 2.75 2.75 2.75 2.75 2.75 Cat. DC1 1.5 2 2.5 3 Cat. D1 1.5 2 2.5 3DBN⁴⁾ 0.20 0.20 0.20 0.20 0.20 0.20 0.20 0.20 ITDA⁵⁾ 2 2 2 2 2 2 2 2Total 84.75 85.25 85.75 86.25 84.75 85.25 85.75 86.25 Key to table 1:¹⁾Dynoadd F1, commercial flow control additive from DYNEA ASA²⁾Tinuvin ® 384, commercial light stabilizer based on a benzotriazole,from Ciba ³⁾Tinuvin ® 152, commercial light stabilizer based on asterically hindered amine, from Ciba ⁴⁾30% strength solution from DBN(diazabicyclononene) in butanol ⁵⁾Isotridecyl alcohol

The respective binder mixtures were adjusted to a flow time of 33seconds from the DIN 4 cup by addition of butyl acetate and theirelectrical resistance at 25° C. was studied by means of a dip probemeasuring cell with an LC 2 conductivity meter from Byk Gardner (inaccordance with DIN 55667). The figures set out in table 2 are eachaverage values from three measurements.

TABLE 2 Comp. Comp. Comp. Comp. Inv. Inv. Inv. Inv. ex. 1 ex. 2 ex. 3ex. 4 ex. 1 ex. 2 ex. 3 ex. 4 Elec- 150 100 90 80 540 410 320 280 tricalresis- tance [kΩ]

The results show clearly that the electrical resistance is heavilydependent, on the one hand, on the amount of catalyst added. Although incomparative example 1, with DBU, a blocking agent having a comparativelyhigh molecular weight was used, it is not possible to achieve the limitspecified in the Problem, the target figure of >200 kohm. That isaccomplished only with the inventive blocking agents described. In orderto achieve sufficient weathering stability on the part of the clearcoatmaterials and to maximize the conversion of the silane crosslinkingreaction, and also to obtain good techno-mechanical properties, it isadvantageous to use as much catalyst as possible.

Formulation of the Coating Compositions and Production of the Coatings

For the investigation of the mechano-technological properties, thecoating compositions of examples 2 to 4 and C1 to C4, prepared using,respectively, the binder mixtures of inventive examples 2 to 4 and thebinder mixtures of comparative examples C1 to C4, were investigated fortheir scratch resistance. For the preparation of the coatingcompositions, 100 parts by weight of each of the binder mixtures weremixed with the number of parts by weight of the partly silanizedisocyanate B1 shown in is table 3, and the mixtures were homogenized.

TABLE 3 Composition of the coating compositions of comparative examplesC1 to C4 and of the coating compositions of inventive examples 2 to 4,in parts by weight Comp. Comp. Comp. Comp. C1 C2 C3 C4 Inv. 2 Inv. 3Inv. 4 Binder 100 mixture C1 Binder 100 mixture C2 Binder 100 mixture C3Binder 100 mixture C4 Binder 100 mixture B2 Binder 100 mixture B3 Binder100 mixture B4 Isocyanate 123.7 123.0 122.3 121.6 122.3 121.6 120.9curing agent B1

For the assessment of the scratch resistance of the coatings, thecoating compositions were applied, shortly after homogenization, inthree spray passes at 2.5 bar, pneumatically, to a commercialsolid-color black waterborne basecoat material from BASF Coatings AG.Thereafter each of the resulting coatings is flushed at room temperaturefor 5 minutes and subsequently baked at 135° C. for 20 minutes. Afterthat the resultant coatings were assessed for their micropenetrationhardness in accordance with DIN EN ISO 14577-1 and also for theirscratch resistance by means of the Crockmeter test [based on EN ISO105-X12 with 10 double rubs and an applied force of 9N, using 9 μmpolishing paper (3M 281Q Wetordry™ Production™), with subsequentdetermination of the residual gloss at 20° using a commercial glossinstrument, after cleaning of the panels with isohexane.0] and the AMTECtest [based on EN ISO 20566:2006, after cleaning of the panels withisohexane.0]. The results obtained are compiled in table 4.

TABLE 4 Residual gloss, Residual gloss, Microhardness Crockmeter, afterAMTEC, after Example [N/mm2] cleaning [%] cleaning [%] Comp.ex. 102.672.5 89.5 C1 Comp.ex. 107.4 79.6 89.5 C2 Comp.ex. 109.7 78.8 91.8 C3Comp.ex. 106.8 76.9 89.5 C4 Example 2 115.4 88.5 89.8 Example 3 119.186.2 91.2 Example 4 119.2 88.4 89.9

The results show that the inventive formulations with the inventivebinder mixtures, with electrical resistance figures of more than 200kohm, exhibit good mechanical properties. The Crockmeter results inparticular are at a better level than those of the comparative examples.

In analogy to the binder mixtures of inventive examples 2 to 4, thebinder mixtures of comparative examples C5 to C8 are prepared from thecomponents specified in table 5.

TABLE 5 Composition of the binder mixtures of comparative examples C5 toC8 in parts by weight Comp. C5 Comp. C6 Comp. C7 Comp. C8 Polyester A136.6 36.6 36.6 36.6 Additive F1 21.0 21.0 21.0 21.0 Butyl acetate 14.714.7 14.7 14.7 Butylglycol 2.1 2.1 2.1 2.1 diacetate Triethyl ortho- 2.12.1 2.1 2.1 formate Dynoadd ¹⁾ 0.20 0.20 0.20 0.20 Tin. 384 ²⁾ 1.60 1.601.60 1.60 Tin. 152 ³⁾ 2.75 2.75 2.75 2.75 Cat. DC2 1.5 3.0 Cat. DC3 1.53.0 DBN ⁴⁾ 0.20 0.20 0.20 0.20 ITDA ⁵⁾ 2 2 2 2 Total 84.75 86.25 84.7586.25 Key to table 5: ¹⁾ Dynoadd F1, commercial flow control additivefrom DYNEA ASA ²⁾ Tinuvin ® 384, commercial light stabilizer based on abenzotriazole, from Ciba ³⁾ Tinuvin ® 152, commercial light stabilizerbased on a sterically hindered amine, from Ciba ⁴⁾ 30% strength solutionfrom DBN (diazabicyclononene) in butanol ⁵⁾ Isotridecyl alcohol

Investigation of the electrical resistance of the formulations gave thefollowing result, shown in table 6:

TABLE 6 Resistances of the binder mixtures of comparative examples C5 toC8 Comp. ex. Comp. ex. Comp. ex. Comp. ex. 5 6 7 8 Electrical resistance140 90 170 130 [kohm]

The results show that the amines having a fairly low molecular weightare not suitable for achieving the figures for electrical resistancethat were required in the Problem.

As a parameter for the use of inventively suitable blocking agents it ispossible to employ the estimation of the hydrodynamic volume:V_(hydr)˜(r_(contour)/2)³. A corresponding estimation of the contourlengths and of the resultant hydrodynamic volumes is shown in table 7below and is based on the assumption of an average bond length of 155 pmand a projected bond angle of 30°. For further details, refer to thetextbook by H. G. Elias, “Makromoleküle”, Hüthig & Wepf Verlag, Basel,Volume 1, “Grundlagen”, page 51.

TABLE 7 Number of Contour Estimated bonds to be lengths hydrodynamicBlocking agent projected [pm] volume [pm³] Tris(ethylhexyl)amine 7 9.3100.5 Dimethylethanolamine 4 5.3 18.6 Morpholine 2 (1) 5.5 20.8 DBU 4(1) 6.9 18.6

In analogy to the binder mixtures of inventive examples 2 to 4, thebinder mixtures of inventive examples 5 to 10 are prepared from thecomponents specified in table 8.

TABLE 8 Composition of the binder mixtures in parts by weight Inv. Inv.Inv. ex. ex. 5 ex. 6 Inv. ex. 7 Inv. ex. 8 Inv. ex. 9 10 Polyester A136.6 36.6 36.6 36.6 36.6 36.6 Additive F1 21.0 21.0 21.0 21.0 21.0 21.0Butyl acetate 14.7 14.7 14.7 14.7 14.7 14.7 Butylglycol 2.1 2.1 2.1 2.12.1 2.1 diacetate Triethyl 2.1 2.1 2.1 2.1 2.1 2.1 orthoformateDynoadd¹⁾ 0.20 0.20 0.20 0.20 0.20 0.20 Tin.384²⁾ 1.60 1.60 1.60 1.601.60 1.60 Tin.152³⁾ 2.75 2.75 2.75 2.75 2.75 2.75 Cat. D2 1.5 2 — — — —Cat. D3 — — 1.5 2 2.5 3 DBN⁴⁾ 0.20 0.20 0.20 0.20 0.20 0.20 ITDA⁵⁾ 2 2 22 2 2 Total 84.75 85.25 84.75 85.25 85.75 86.25 Key to table 8:¹⁾Dynoadd F1, commercial flow control additive from DYNEA ASA²⁾Tinuvin ® 384, commercial light stabilizer based on a benzotriazole,from Ciba ³⁾Tinuvin ® 152, commercial light stabilizer based on asterically hindered amine, from Ciba ⁴⁾30% strength solution from DBN(diazabicyclononene) in butanol ⁵⁾Isotridecyl alcohol

The respective binder mixtures of inventive examples 5 and 6 wereadjusted to a flow time of 33 seconds from the DIN 4 cup by addition ofbutyl acetate and—as described for inventive example 1—their electricalresistance was studied by means of a dip probe measuring cell with an LC2 conductivity meter from Byk Gardner (in accordance with DIN 55667).This produced the figures set out in table 9:

TABLE 9 Inv. Inv. Inv. Inv. ex. ex. 5 ex. 6 Inv. ex. 7 Inv. ex. 8 ex. 910 Electrical 260 220 570 420 380 300 resistance [kΩ]

The binder mixtures of inventive examples 7 to 10, however, show atendency toward crystallization of the catalyst, and so, preferably, acrystallization inhibitor is added as well. It is likewise possible toblock the catalyst with a mixture of dodecyldimethylamine andisododecyldimethylamine.

1. A binder mixture based on aprotic solvents, comprising ahydroxyl-containing compound (A) and at least 1.0% by weight, based onthe nonvolatile constituents of the mixture, of a phosphorus- andnitrogen-containing catalyst (D) for the crosslinking of silane groups,wherein the mixture comprises (iii) as hydroxyl-containing compound (A)at least one hydroxyl-functional polyester (A) in which on average atleast one hydroxyl function of the polyester is esterified with at leastone acid selected from the group of the isomeric C8 to C9 monocarboxylicacids, and (iv) as catalyst (D) phosphorus-containing catalyst blockedwith an amine of the formula (I)

where R₁ is an acyclic aliphatic or araliphatic hydrocarbon radicalhaving at least 3 carbon atoms, R₂ is an acyclic aliphatic oraraliphatic hydrocarbon radical which is the same or different from R₁and/or R₃, and R₃ is hydrogen or an acyclic aliphatic or araliphatichydrocarbon radical which is the same or different from R₁ and/or R₂. 2.The binder mixture of claim 1, wherein one or more of the radicals R₁,R₂, and R₃ are selected from the group consisting of aliphatichydrocarbon radicals having 6 to 18 carbon atoms, branched aliphatichydrocarbon radicals having 6 to 18 carbon atoms, and mixtures thereof.3. The binder mixture of claim 1, wherein the amine-blocked,phosphorus-containing catalyst (D) comprises at least one tertiary amineof the formula (I) having a contour length of more than 8 pm as blockingagent.
 4. The binder mixture of claim 1, wherein the amine-blocked,phosphorus-containing catalyst (D) is selected from the group consistingof amine-blocked substituted phosphonic diesters, amine-blockedsubstituted diphosphonic diesters, amine-blocked substituted phosphoricmonoesters, amine-blocked substituted phosphoric diesters, and mixturescomprising two or more of the foregoing.
 5. The binder mixture of claim1, further comprising a crystallization inhibitor if in the amine (I)either (i) R₃ is hydrogen and R₁ and R₂ are linear aliphatic hydrocarbonradicals or (ii) all radicals R₁, R₂ and R₃ are linear aliphatichydrocarbon radicals.
 6. The binder mixture of claim 1, furthercomprising a light stabilizer based on sterically hindered amines (HALS)and a UV absorber.
 7. The binder mixture of claim 1, wherein thehydroxyl-functional polyester (A) is a hyperbranched, dendritichydroxyl-functional poly-ester in which on average at least one hydroxylfunction of the polyester is esterified with at least one acid selectedfrom the group of the isomeric C8 to C9 monocarboxylic acids.
 8. Thebinder mixture of claim 1, wherein the hydroxyl-functional polyester (A)has an OH number ≧150 mg KOH/g, determined in accordance with DIN 53240,and/or a hydroxyl functionality (provided by the number of free andesterified hydroxyl groups in the polyester) of greater than
 16. 9. Thebinder mixture of claim 1, wherein the hydroxyl-functional polyester (A)has one or more characteristics selected from the group consisting of anacid number ≦8.0 as determined in accordance with DIN 53402, anumber-average molecular weight of 1500-4000 g/mol, as determined viaGPC with a polystyrene standard in THF with 0.1% by weight acetic acid,a poly-dispersity Mw/Mn <4, and combinations comprising two or more ofthe foregoing.
 10. The binder mixture of claim 1, which has anelectrical resistance to DIN 55667 of at least 200 kohm at 25° C.
 11. Acoating composition comprising the binder mixture of claim 1 and atleast one saturated compound (B) with isocyanate groups, which comprisesat least partly hydrolyzable silane groups.
 12. The coating compositionof claim 11, wherein the compound (B) comprises between 2.5 and 97.5 mol%, based on the entirety of structural units (III) and (IV), of at leastone structural unit of the formula (III)—N(X—SiR″x(OR′)3-x)n(X′—SiR″y(OR′)3-y)m  (III) where R′=hydrogen, alkylor cycloalkyl, it being possible for the carbon chain to be interruptedby nonadjacent oxygen, sulfur or NRa groups, with Ra=alkyl, cycloalkyl,aryl or aralkyl, X, X′=linear and/or branched alkylene or cycloalkyleneradicals having 1 to 20 carbon atoms, R″=alkyl, cycloalkyl, aryl, oraralkyl, it being possible for the carbon chain to be interrupted bynonadjacent oxygen, sulfur or NRa groups, with Ra=alkyl, cycloalkyl,aryl or aralkyl, n=0 to 2, m=0 to 2, m+n=2, and x, y=0 to 2, and between2.5 and 97.5 mol %, based on the entirety of structural units (III) and(IV), of at least one structural unit of the formula (IV)—Z—(X—SiR″x(OR′)3-x)  (IV), where Z=—NH—, —NR—, —O—, with R=alkyl,cycloalkyl, aryl or aralkyl, it being possible for the carbon chain tobe interrupted by nonadjacent oxygen, sulfur or NRa groups, withRa=alkyl, cycloalkyl, aryl or aralkyl, x=0 to 2, and X, R′, R″ have thedefinition stated in the case of formula (III).
 13. A multistage coatingmethod which comprises applying a pigmented basecoat film to anoptionally precoated substrate and thereafter applying a film of thecoating composition of claim
 11. 14. A method of making an automotiveOEM finish or automotive refinish, comprising applying the coatingcomposition of claim 11 as a clearcoat material to a substrate.
 15. Amulticoat effect and/or color paint system comprising at least onepigmented basecoat and at least one clearcoat disposed thereon, whereinthe clearcoat has been produced from the coating composition of claim11.
 16. The binder mixture of claim 1, wherein all three radicals R₁,R₂, and R₃ are branched aliphatic hydrocarbon radicals having 8 to 14carbon atoms.
 17. The binder mixture of claim 4, wherein theamine-blocked, phosphorus-containing catalyst (D) is selected from thegroup consisting of amine-blocked acyclic phosphoric diesters,amine-blocked cyclic phosphoric diesters, amine-blocked phosphoric acidalkyl esters, amine-blocked phosphoric acid phenyl esters, amine-blockedphosphoric acid phenyl esters, and mixtures comprising two or more ofthe foregoing.
 18. The binder mixture of claim 4, wherein theamine-blocked, phosphorus-containing catalyst (D) is phenyl phosphateblocked with tris(ethylhexyl)amine.
 19. The binder mixture of claim 1,comprising 2.0% to 7.0% by weight, based on the nonvolatile constituentsof the mixture, of the phosphorus- and nitrogen-containing catalyst (D).20. The coating composition of claim 11, which comprises as solventbutyl acetate or a solvent mixture comprising butyl acetate.